A lithium primary battery has excellent characteristics such as very high electromotive force, and is used for various purposes which utilize this characteristic. Especially, a lithium primary battery using manganese dioxide for a positive electrode is applied for many purposes, for example, for a camera, memory back-up, meter device, and the like, because it has excellent high rate discharge characteristics and discharge characteristics at a low temperature.
Addition of boron to manganese dioxide has been proposed for inhibiting an increase of internal resistance of a battery as a discharge reaction progress in Japanese Patent Laid-open publication No. 11-339794. It has also been proposed to use manganese dioxide obtained by electrolytic oxidation by performing electrolysis in an electrolyte bath containing phosphoric acid in Japanese Patent Laid-open publication No. 2-256163.
However, use of a lithium primary battery has been expanded and there are requests for further improved storage characteristics especially in a use of the battery for memory back-up, meter device, and the like. Manganese dioxide free of impurities and manganese dioxide including boron or phosphorous as described in the above mentioned Japanese Patent Laid-open publications have been used. However, there is a problem that the battery does not have sufficient storage characteristics because manganese dioxide is dissolved in an electrolyte during storage and the dissolved manganese dioxide deposits on a negative electrode.